1. Field of the Invention:
The present invention relates to a metering device, and particularly to a metering device, which provides a weighing platform and is possible to sense and control the weight of delivered substances much more accurately.
2. Description of Related Art:
A prior art of metering device as shown in FIG. 1 provides a feeding funnel axe2x80x2 being disposed above a series of feeding device bxe2x80x2 and weighed substances are fed to the feeding devices bxe2x80x2 sequentially through the feeding funnel axe2x80x2. Then, the substances are sent out by way of the feeding device and fall into a scale barrel 10xe2x80x2. A weight part 20xe2x80x2 at a lateral side of the scale barrel 10xe2x80x2 senses the weight of the weighed substances in the scale barrel 10xe2x80x2. When a predetermined value of weight set up in the weight part 20xe2x80x2 is going to reach, the feeding speed may slow down to deliver a very small amount of weighed substance or single weighed substance till the predetermined value exactly reached. At this time, a movable box plate of the shut mechanism cxe2x80x2 may open to admit the weighed substances falling down to a packing bag so as to complete the operation of metering. Referring to FIG. 2, a micro-feeding mechanism cxe2x80x2 is mounted beside or above a feeding device bxe2x80x2. When the weight part 20xe2x80x2 has sensed the predetermined value is going to reach, the feeding device bxe2x80x2 stops to deliver the weighed substances such that the micro-feeding mechanism cxe2x80x2 then send out a very small amount of weighed substance or single weighed substance slowly. When the predetermined value is exactly reached, the micro-feeding mechanism stops running and the movable box plate 12 of the shut mechanism 30xe2x80x2 admits the weighed substances falling down to the packing bag so as to complete the operation of metering.
Referring to FIG. 3, a further conventional metering device provides a rotating threaded rod b1xe2x80x2 in the feeding device bxe2x80x2 to send weighed substances into the scale barrel 10xe2x80x2. When the weight part 20xe2x80x2 has sensed the predetermined value is going to reach, the rotating speed of the threaded rod is slow down to send out a very small amount of weighed substance. When the predetermined value is exactly reached, the threaded rod stops rotating and the movable box plate 12 of the shut mechanism 30xe2x80x2 admits the weighed substances falling down to the packing bag so as to complete the operation of metering.
It can be understood that there is a large difference of elevation between the scale barrel 10xe2x80x2 and the micro-feeding mechanism cxe2x80x2 and/or the feeding device bxe2x80x2 for the prior art. That is, weighed substances falling down from the scale barrel 10xe2x80x2 to the micro-feeding mechanism and/or the feeding device bxe2x80x2 takes a long way. Hence, it may result in a long responding time for measuring weight and a greater acceleration of gravity of the weighed substances. Moreover, these factors affect the accuracy of weight sensing performed by the weight part 20xe2x80x2 substantially.
A main object of the present invention is to provide a metering device, with which a weighing platform at least at a lateral side of the scale barrel is mounted to touch falling weighed substances before the scale barrel receiving the weighed substances. Therefore, a metering operation can be accurately performed and easily controlled.
Another object of the present invention is to provide a metering device, with which a moving rod in the shut mechanism has both ends thereof be pivotally attached by a connecting rod respectively extending along lateral outer sides of the movable box plate. A free end of the connecting rod is provided a groove to fit with a projecting piece on a stationary box plate while the movable box plate is in a state of closing to keep the movable box plate from moving accidentally.